EP0730096B1 - Diffusionspumpe - Google Patents

Diffusionspumpe Download PDF

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Publication number
EP0730096B1
EP0730096B1 EP96301396A EP96301396A EP0730096B1 EP 0730096 B1 EP0730096 B1 EP 0730096B1 EP 96301396 A EP96301396 A EP 96301396A EP 96301396 A EP96301396 A EP 96301396A EP 0730096 B1 EP0730096 B1 EP 0730096B1
Authority
EP
European Patent Office
Prior art keywords
guard ring
outer body
chimney
pump
oil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP96301396A
Other languages
English (en)
French (fr)
Other versions
EP0730096A1 (de
Inventor
Graeme Huntley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BOC Group Ltd
Original Assignee
BOC Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BOC Group Ltd filed Critical BOC Group Ltd
Publication of EP0730096A1 publication Critical patent/EP0730096A1/de
Application granted granted Critical
Publication of EP0730096B1 publication Critical patent/EP0730096B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F9/00—Diffusion pumps
    • F04F9/06—Arrangement of vapour traps

Definitions

  • This invention relates to vacuum pumps of the type known as diffusion pumps.
  • Diffusion pumps are well known and widely used for the attainment of high and ultra high vacuum. When used with modern working fluids and accessories, they can produce pressures approaching 10 -10 mbar. The pumps are generally incapable of exhausting directly to the atmosphere and require the use of a backing pump, commonly an oil sealed rotary vacuum pump, in conjunction with the diffusion pump itself.
  • Diffusion pumps generally comprise a substantially cylindrical outer body which is cooled by, for example, coils helically wound around the outside of the body through which cooling water can be circulated or alternatively by air cooled fins attached to the outside of the body.
  • the outer body Within the outer body is positioned a hollow "chimney sitting at, or close to, the base of the outer body and which tapers (continuously or, more usually, in stages) upwardly from the base.
  • the chimney is generally contained within the outer body and is positioned substantially concentrically therein.
  • top cap having a generally circular portion of somewhat larger diameter than the top of the chimney and positioned symmetrically with regard to the chimney and having a downwardly projecting annular side portion whose lower edge is somewhat beneath the upper edge of the chimney.
  • the top cap is therefore substantially an inverted "cup shaped" component positioned about the top of the chimney with a circular or annular passageway therebetween.
  • a heater is provided in the base of outer body and, prior to use of the pump, a working oil is placed in the base of the body to a height above the lower edge of the chimney positioned within the body.
  • the oil is usually a low vapour pressure oil although some versions of diffusion pumps use mercury.
  • a pump inlet is positioned in the outer body above the top cap and an outlet in the side of the body towards the base of the chimney but above the oil level.
  • the outlet is normally connected to a backing pump as described above.
  • the inlet of the pump is normally closed by a valve initially and the backing (rotary) pump is turned on and left running continuously, a pressure of at least 0.1 mbar being required on the exhaust side of the diffusion pump.
  • the cooling system (water or air) for the outer body is turned on and the oil can now be heated by the heater for, for example, fifteen to twenty minutes, when it begins to boil.
  • Hot vapour rises up the chimney and forms (aided by the taper) a relatively high oil pressure at the top of the chimney.
  • the vapour is then urged through the passageway between the chimney and the top cap to an area of much lower pressure and creates an annular vapour jet (or "jet nozzle").
  • This jet is designed to move at a velocity which is supersonic and which impinges on the inside surface of the cooled outer body where the vapour condenses and condensed oil flows down the inside wall of the outer body and returns to the oil reservoir at the base of the body.
  • guard ring or “cold cap”
  • a guard ring may comprise a cooled surface positioned above the top cap and in substantially thermal isolation therefrom.
  • it could have the same overall shape, for example substantially “cup-shaped”, but of larger size in order to shroud the top cap.
  • the guard ring may be more complicated and present more cooled surfaces to any oil molecules attempting to escape towards the diffusion pump inlet.
  • baffle which comprises a number of cooled surfaces to condense back streaming vapour molecules.
  • a baffle is commonly present in a self contained component which can be positioned between a diffusion pump inlet flange and the chamber being evacuated.
  • baffles tend to detract from the ability to minimise the size, height and/or general complexity of a diffusion pump as a whole.
  • French patent 2 220 691 discloses a diffusion pump including an outer cooled body in which is located a vapour jet assembly.
  • a guard ring is positioned above the top cap of the vapour jet assembly and a baffle assembly is positioned above the guard ring.
  • the baffle is thermally isolated from the guard ring and is cooled by a Peltier device.
  • a heater is provided for heating a working fluid when present in the outer body to cause evaporated fluid to pass up a chimney forming part of the vapour jet assembly.
  • a diffusion pump comprising an outer body; means for cooling the outer body; chimney means positioned within the outer body; a top cap positioned about the top of the chimney means to form an annular passageway (or an array of passageways) therebetween; a guard ring positioned generally above the top cap; means for cooling the guard ring; baffle means contained substantially wholly within the outer body and substantially thermally isolated from the guard ring; a Peltier device for cooling the baffle means; and heater means for heating a working fluid when present in the outer body to cause, in use, evaporated oil to pass up the chimney means characterised in that the Peltier device is connected between the guard ring and the baffle means with the relatively "cold" end of the device in good thermal contact with the baffle means and the relatively “warm” end of the device in contact with the guard ring.
  • the baffle means is present within the guard ring itself.
  • Such feature of the invention allow for a more compact design of diffusion pump that can be more compact, shorter and be one which can be contained within a single body without any protrusions therefrom.
  • a diffusion pump comprising an outer body 1 having
  • the portion 4 and the upper part of the portion 3 have annular cooling fins 6 attached to the outside surface thereof and on one side of the outer body is a cooling fan 7 for producing in use, a supply of cooling air to the fins 6 in particular.
  • a chimney 8 is positioned within the outer body 1 having a base portion 9 of circular cross section such that it fits tightly within the base portion 2 of the body 1.
  • the chimney 8 also has upper portions of different cross sections but generally presenting a tapered component narrowing towards the top. At the top, however, a small flared portion 10 which communicates the inside of the chimney with the inside of the body portion.
  • a top cap 11 is positioned about the flared portion 10 of the chimney being generally of circular "cup shape" and defining an annular array of passageways 12 between it and the flared portion 10.
  • a generally circular guard ring 13 which is attached to the top portion 5 and which has a central portion 14 which extends across and above the top cap 11.
  • the top cap 11 is in fact held in position by means of a spring 15 between the portion 14 and the top cap 11.
  • the guard ring as a whole by virtue of its contact with the cooled outer body 1 in particular, is cooled by means of the cooling fins/fan arrangement for cooling the body as a whole.
  • the top cap 11 itself is not cooled as little heat is conducted via the spring 15.
  • a baffle means 16 is provided which is generally within the top portion 5 and shaped such that it presents a surface at the inlet to the pump with a circular hole 17 through which gas being pumped can pass.
  • the baffle means also has an annular downwardly extending portion 18 contained concentrically within the guard ring 13 such that an annular passageway is formed within the portion 18 for gas passing in to the pump via the hole 17.
  • a Peltier device 19 connects the upper surface of the central portion 14 of the guard ring 13 and the lower surface of a central portion 20 of the baffle means 16; this is the only thermally conducting connection between the guard ring and the baffle means.
  • the Peltier device is orientated such that its cold face abuts the baffle means and its warm face about the guard ring. Electrical connection to the Peltier device is effected via the channel 21.
  • the pump also possesses an outlet 22 which leads via a pipe 23 to a flange 24 to which in use is attached a backing pump, normally an oil sealed rotary pump of known construction. Beneath the flange 24 is a backing condenser 25 also of known construction and of no relevance to the invention.
  • a heater 26 is positioned at the base of the chimney.
  • the backing pump is turned on to reduce the pressure within the diffusion pump, normally with the inlet of the diffusion pump closed, and the cooling fan turned on.
  • Heating of the oil causes oil vapour to rise up the chimney in the general manner described above and to emerge through the annular array of passageways 12 and thereafter to fall downwardly in the general direction shown by the arrows in to the cooled inner surface of the portion 4 in particular.
  • the top cap 11 is hot by virtue of the impingement thereof of the hot oil vapour but the guard ring 13 surfaces generally and its central portion 14 in particular are cool and assist in condensing any oil vapour which impinges thereon.
  • the presence of, and the positioning of, the baffle means within the upper part of the guard ring 13 should ensure that any backstreaming oil vapour is effectively condensed and allow to fall into the base of the outer body/chimney (connection for the oil therebetween not shown) for re-use in the continuing pump operation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Non-Positive Displacement Air Blowers (AREA)

Claims (3)

  1. Diffusionspumpe mit einem Außengehäuse (1), Mitteln (6, 7) zum Kühlen des Außengehäuses (1), innerhalb des Außengehäuses (1) positionierten Abzugsmitteln (8), einer um das obere Ende der Abzugsmittel (8) positionierten Haube (11) zur Bildung eines dazwischen liegenden ringförmigen Kanals (oder einer Anordnung von Kanälen (12)), einem im wesentlichen über der Haube (11) positionierten Schutzring (13), Mitteln (6, 7) zum Kühlen des Schutzrings (13), im wesentlichen vollständig im Außengehäuse (1) enthaltene Leitmittel (16), die vom Schutzring (13) im wesentlichen thermisch isoliert sind, einem Peltier-Gerät (19) zum Kühlen der Leitmittel (16), und Heizmitteln (26) zum Erwärmen eines Arbeitsmittels, wenn dieses im Außengehäuse (1) vorhanden ist, um im Gebrauch verdampftes Öl in den Abzugsmitteln (8) nach oben strömen zu lassen, dadurch gekennzeichnet, daß das Peltier-Gerät (19) zwischen dem Schutzring (13) und den Leitmitteln (16) angeordnet ist, wobei das relativ "kalte" Ende des Geräts in gutem thermischen Kontakt mit den Leitmitteln (16) und das relativ "warme" Ende des Geräts in Kontakt mit dem Schutzring (13) steht.
  2. Diffusionspumpe nach Anspruch 1, wobei die Leitmittel (16) innerhalb des Schutzrings (13) angeordnet sind.
  3. Pumpe nach Anspruch 1 oder 2, wobei die Leitmittel (16) sich auf einer kühleren Temperatur als der Schutzring befinden.
EP96301396A 1995-03-03 1996-02-29 Diffusionspumpe Expired - Lifetime EP0730096B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9504260.2A GB9504260D0 (en) 1995-03-03 1995-03-03 Improvements in diffusion pumps
GB9504260 1995-03-03

Publications (2)

Publication Number Publication Date
EP0730096A1 EP0730096A1 (de) 1996-09-04
EP0730096B1 true EP0730096B1 (de) 2002-07-17

Family

ID=10770565

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96301396A Expired - Lifetime EP0730096B1 (de) 1995-03-03 1996-02-29 Diffusionspumpe

Country Status (5)

Country Link
US (1) US5700134A (de)
EP (1) EP0730096B1 (de)
JP (1) JPH08320000A (de)
DE (1) DE69622300T2 (de)
GB (1) GB9504260D0 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6093001A (en) * 1997-05-02 2000-07-25 University Of Pittsburgh Rotary pump having a bearing which dissipates heat
WO2009109995A2 (en) * 2008-02-11 2009-09-11 Yadapalli Kondala Rao A vaccum pump suction filter meant for collecting impurities from function
CN105298943B (zh) * 2015-11-27 2017-06-06 辽宁真龙真空设备制造有限公司 大抽速卧式油增压泵
CN119393394B (zh) * 2024-12-10 2025-11-18 肇庆市东荣真空设备制造有限公司 一种油扩散泵的环形喷嘴结构

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1339121A (en) * 1972-04-26 1973-11-28 British Oxygen Co Ltd Vapour vacuum pumps

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2078788A (en) * 1934-11-09 1937-04-27 Vickers Electrical Co Ltd Diffusion vacuum pump
GB526507A (en) * 1939-03-18 1940-09-19 Frank Edmund Bancroft Improvements in condensation vacuum pumps
US2855140A (en) * 1956-04-24 1958-10-07 Jr John Sedlacsik High vacuum pump
DE1273740B (de) * 1961-05-10 1968-07-25 Jewgenij Andrejewitsch Kolenko Dampffaenger fuer Diffusionspumpen
GB1066971A (en) * 1963-05-30 1967-04-26 Edwards High Vacuum Int Ltd Improvements in or relating to vacuum pumps
FR2163945A5 (de) * 1971-12-07 1973-07-27 Cit Alcatel
US3801225A (en) * 1972-05-12 1974-04-02 British Oxygen Co Ltd Vacuum pumps
GB1448752A (en) * 1973-03-08 1976-09-08 Boc International Ltd Vacuum pumping assembly
US4108576A (en) * 1976-07-06 1978-08-22 Varian Associates, Inc. Low cost, thermally efficient diffusion pump
US4845360A (en) * 1987-12-10 1989-07-04 Varian Associates, Inc. Counterflow leak detector with high and low sensitivity operating modes
US5137429A (en) * 1991-04-15 1992-08-11 Spectrameasure Inc. Diffusion pump

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1339121A (en) * 1972-04-26 1973-11-28 British Oxygen Co Ltd Vapour vacuum pumps

Also Published As

Publication number Publication date
GB9504260D0 (en) 1995-04-19
DE69622300T2 (de) 2002-11-14
US5700134A (en) 1997-12-23
EP0730096A1 (de) 1996-09-04
JPH08320000A (ja) 1996-12-03
DE69622300D1 (de) 2002-08-22

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